A bomb squad was called to a hotel after items were hurled into the building.
ACT Policing raced to the Hyatt Hotel Canberra on Commonwealth Avenue at about 9am on Wednesday after reports of a disturbance.
Officers believe two people threw rocks and a suspicious item at the building, causing minor property damage. No one was injured.
The item was seized by the AFP Bomb Response Team who determined the item was not an explosive device.
Witnesses were heard yelling amid confusion in the hotel, where a defence conference was due to take place, The Canberra Times reported.
ADM Congress, an annual summit, was due to kick off around the same time at the venue.
Significant figures in the sector are due to speak, including Minister for Defence Industry Pat Conroy, Chief of Navy Vice Admiral Mark Hammond, and the Australian Army’s Head Land Systems Major General Jason Blain.
The opening day of the conference has not been interrupted by the incident.
A rock was thrown through the window of Hyatt Hotel Canberra on Wednesday morning
A federal bomb response team is investigating the incident
Police then searched the hotel about midday and found unattended backpacks in a conference room.
People were removed from the room to another part of the hotel while it was searched and the bag was assessed.
Half an hour later, the bags were deemed to not be suspicious and the owners were located.
The ACT Joint Counter Terrorism Team, which includes officers from AFP Counter Terrorism, ACT Policing and Australian Security Intelligence Organisation, said they are monitoring the response.
